Line-at-a-time printer



Feb. s, 1966 H GROTTRUP 3,233,540 LINE-AT-A-TIME PRINTER 2 Sheets-Sheet1y Filed April 25, 1965 n 1 1 r 1 c I NVEN TOR.

ATTORNEY Feb. 8, 1966 H. GRo'r-rRUP LINE-AT-A-TIME PRINTER 2Sheets-Shea?l 2 Filed April 23, 1965 Il Il Il Il Il Il Il Il Il Il Il IlIl Il /l Il Il n INVENTOR.

/EML/' GROTTRUP BY @w 6% .ATTORNEY Vfor lthe printing purpose.

United States Patent O 3,233,540 LlNE-A'I`ATIME PRINTER Helmut Grottrup,Pforzheim, Germany, assignor to International Standard ElectricCorporation, New York, N.Y., a corporation of Delaware Filed Apr. 23,1965, Ser. No. 450,465 3 Claims. (Cl. lill-93) This application is acontinuation-inpart of my prior application Serial No. 153,144 filedNovember 17, 1961, now abandoned.

The present invention relates to a line-at-a-time printer. Such types ofprinting devices have been known for some time in the relevant art inthe form of mosaic printers, in which the* characters are constituted byindividual points, e.g. by an array consisting of 5 times 7 pointelements. Various ways have already been proposed for producing thecharacters. One simple way consists in assembling 35 wires in the formof a writing head, and bundling these wires in such a way thattheir endsform an approximately plane surface, the size of which corresponds tothat of the characters to be printed. Independently of one another,these wires can be pushed out of this surface and against the printingsurface. There are two ways of selecting the respective wires necessaryfor the printing purpose: either each individual wire is actuated by anelectromagnet of its own, or the entire wire pack is pushed against aperforated template which permits the passage of only those wires whichare required Instead of the perforated ternplate it is also possible touse a template comprising a certain arrangement of bosses. In this case,the template is adjusted in such a day that the wires to be printedoppose the bosses; thereupon the template is pushed against the wirepack. In order to enable the simultaneous printing of severalcharacters, a corresponding number of writing heads may be juxtaposed.Since in general the characters are required to be arranged more closelyto each other than the writing heads with their actuating mechanisms canpossibly be arranged, one known proposal is to provide several heads, ofwhich each one is assigned to several printing positions. In this casethe printing is effected simultaneously. After the printing, the writingheads arranged in one line are displaced side ways, so that the nextcharacters can be printed in the same line.

Instead of prin-ting the m-times-n point array as a whole, it may alsobe built up in a row-wise fashion. In this case the writing heads onlyconsist of either m or n wires respectively, and either the writing headis moved over the paper, or the paper is moved past the writing head.The actuation of the printing wires is effected by individuallyenergized electromagnets; Also in this case several Writing-heads may bearranged in such al way that simultaneously either several or allcharacters of one printing line can be built up. The row-wiseconstruction of the characters is preferred because the paper can bemoved continuously past the heads, thus permitting attainment ofextremely high operating speeds. However, since the actuating magnetsoccupy a certain space in the length or width of the printing line,which cannot be` reduced, the characters cannot be printed as closely toeach other as would be desirable from the legibility point of view. Thisdisadvantage could be eliminated by arranging the writing heads inseveral staggered rows, but this would entail a considerableexpenditure, and an enlargement in size of the printing device.

In particular, the present invention relates to a wire printed of thelast mentioned kind, a line-at-a-time printer in which the characters ofone printing line are composed in a row-wise manner from above to below,but in which a continuous, that is, uninterrupted printing of thecharac- ICC ters can be carried out with a minimum thickness of theprinting wires. In `the conventional manner, printing mechanisms can beused in which the wires are not assembled in printing heads, but areindividually controllable by the action of electromagnets.

The general idea of the invention consists in providing onesingleelectromagnet for the actuation of all typeprinting elements, and indesigning the individual typeprinting elements to act as the armature ofthis electromagnet which is provided in common to all type-printingelements or groups of type-printing elements, and in designing thearmatures, in turn, as electrically conductive angular levers eachconsisting, in the direction of the lines, of a thin sheet of metal,with its center of rotation lying outside the electromagnet, so thatupon energization of the electromagnet, a lug provided at the angularlever is pressed against the printing ribbon. lFor selecting thetype-printing elements to be actuated, there is provided anelectrostatic or magnetic device which, upon energization, has aretarding effect upon the angular levers and thus controls the selectiveprinting operation of the typeprinting elements.

The action of frictional forces, produced in electrostatic clutches, isknow per se. The electrostatic force may therefore be produced in anyknown manner. The resetting of the type-printing elements can beeffected witl the aid of a mechanical spring; however, it is moreappropriate to provide a magnetic resetting in such a way that theangular levers are reset to normal by a second common magnet after theprinting process has been performed` The invention will now be explainedin detail with reference to exempliiied embodiments shown in FIGS. 1-4of the accompanying drawings, in which:

FIG. l is a side view of Ia unitary structure containing vetype-printing elements and showing the electrostatic control arrangementaccording to the invention;

FIG. la is an end view of the structure o FIG. 1;

FIG. 2 is a section taken on the line A-A of FIG. l;

FIG. 3 is a section taken on the line B-B of FIG. l; and

FIG. 4 shows a modified type of embodiment of the type-printing elementaccording to the invention.

In `the drawings the cross-sections .are not shown in a true scale, but,especially in the dimension extending in parallel rela-tion to the line,in an extremely distorted fashion, in order to enable a betterunderstanding of the detail-s.

It is assumed that for each character there are required fivetype-printing elements, and two type-printing elements for each space,so that altogether seven times more type-printing elements are requiredthan characters to be written in one line. The individual elements 1 arepivotably .arranged on a shaft 2 which is common to all elements. On theupper right-hand side there is provided a lug 3 forming a printing pointwhich, after a corresponding movement of the type-printing element, isadapted to hit the ink ribbon 4. The lower parts of all elements 1project into a space which is defined by two Ymagnets 5 and 6corresponding to the length of the line.

These magnets are manufactured in the conventional manner from two polepieces with intermediately arranged wound cores. The magnet 6 is thereset magnet, that is, the magnetic spring for resetting alltype-printing elements to normal. The magnet 5V operates as a printingmagnet to bring all type-printing elements against the limit stop in theprinting plane. The type-printing elements, in their lower portion 7,are of a stronger design than in their upper portion 8. The portion 8 isinserted in a silghtly movable way into a gap between two foils ofinsulating material 9. On the other side of each of these two insulatingfoils 9 are two electrically conductive foils which are respectivelyfollowed by a further insulating foil 11. lThe foils 10 may also bedesigned as met-al coatings of the foils 9. Between the two foils 9, andin the space which is not occupied by the' portion 8 of thetype-printing elements, there is arranged -a still thicker sheet-metalmember i2 which is provided with a soldering terminal 13. p Theysolderingterminals of successively following sheet-metal members 12 arestaggered, as shown in FIGS. 1 and 1a. .The metal foils 10, or thecorresponding coatings, for each of the type-printing elements areconductively connected to the connecting sheetmetal member 12 by way ofslots provided in the foils 9, or by corresponding bosses or the likeprovided on the connecting sheet-metal member 12. The foil packsassociated with the portions 7, 8 of the type-printing elements areseparated from one Ianother by intermediate members 14, and are arrangedon the shaft 15, 16y in an insulated manner. This shaft chieflyfacilitates the centering of the Whole block. The actual assembly iseffected by the shafts 17 and the intermediate layer members 18.

This novel type of line-at-a-tirneprinter operates with a continuouspaper feed, 4as follows: Firmly coupled to the feed shaft is a switchingWheel arrangement which I'alternately energizes the magnets 5 and 6. Forthe control of these magnets and for selectively controlling the typeelements electro-statically, I have shown a switching wheel comprisingthree switching commutators 19, 29, and 21. Each of these commutatorshas alternately insulating Iand conducting circumferential portions andcooperating wipers. The commutators 19 and 2o are connected to ground.The former controls the resetting of the type elements by a wiper 21which is connected t-o the coil of the reset magnet 6, the other end ofthe coil being connected to battery. The conducting portions ofthecommutator 19 are shown larger than the insulating portions to givesuicient time for the electrostatic foils to be discharged andindividually charged while the type elements are held in the resetposition.

The commutator Zit has been shown with the insulating portions largerthan the conducting portions, and a Wiper 22 is connected to the coil ofthe magnet 5 the other end of which is connected to battery. The wiper22 is on a conducting portion of the commutator when the wiper 21 is onan insulta-ting portion of the commuft'ator 19. Upon energization o-fthe magnet 5, all typeprinting elements are caused to hit the printingsurface for producingthereon a mosaic point, provided that they are notprevented from performing this movement by the action of theelectrosta-tic friction between the foils. During the reset, which iseffected by the magnet 6, the metal foils or coatings 1t) are. first ofvall discharged via the soldering terminals 13 and Wipers 23, 24, 25, 26,and 27 which are at that moment in contact with the conducting portionsof commutator 2d, and are thereupon individually charged. For chargingthe individual foils 10 and connected members 12, the coinmutator 21 maybe used; This com-mutator is insulated from the common shaft byinsulating sleeve 28 and is connected to battery. A wiper 29 rests on aconducting portion of the commutat-or 21 as long as the reset magnet isoperated.0 Itis connected-to switches 30 by means of which selected'ones of the foil'packs can be connected to battery during this timeandthus charged. The non-charged foilpacks permit the free movement ofthe portionsl 7, 8 of thetype-printing element when the magnet 5 is nextoperated.- The charged foil packs prevent this movement on account'ofthe friction appearing between the foilsV and the portion 8 of thetype-printing element, and caused .by the electrostatic` force. Thetype-printing elements themselves are in this case'A always applied toground potential via the common shaft 2.

FIG. 4 shows another possible embodiment of a typeprinting element,wherein the elements are provided with a lower inertia than in the caseof the already described Cit type of printer. This is of advantage incases where the printing speed is very high.

In principle, however, neither this type-printing element nor theactuation thereof differs from what has been described hereinbefore.Thus, also in this case, the individual elements 1 are capable of beingswivelled about the common shaft 2. In this case, however, the twoele'ctromagnets are arranged in a different way, i.e. in such a way thatthe portion 8 of the type-printing elements performs a lateral movementas indicated by the double-ar row 19 (FIG. 4). Accordingly, the travelof the typeprinting elements is smaller than in the embodiment shownin'FIGS. 1-3, wherein the type-printing elements are pulled forward outof the foil pack.

The electrostatic operation in the second example bears a resemblance tothat shown in the first example and therefore does not require anyfurther explanation.

The particular advantage of this novel type of printer over theconventional types of printers resides in the fact that a mechanicalspreading of `structural elements is avoided. This is made possible bythe employment of electrostatic forces. This, in turn, has the advantagethat the friction-producing forces are only used to perform aretardingprocess, thusy restricting the wear of the f rubbing surface to aminimum.

The basic arrangement as shown in the drawings may b-evfuther extendedfrom the technological point of View. Thus, under certain circumstances,it may be appropriate to construct the electrostatic retarding devicefrom simple stampings which, at the respective points, are coated with ahighly insulating and wear-resistant lacquer. The portions 7 and 8 ofthe type-printing element may also be composed of a relatively thin`sheet-metal member in the middle and of two stuck-on sheet-metalmembers on either side thereof for strengthening the portion y of theelement l.

While have described the principles of my invention in connection withspecific apparatus, it is to be clearly understood that this descriptionis made only by way of example and not as a limitation to the scope ofmy invention as set forth in the accompanying claims.

Iiclaim:

1. A printing apparatus comprising:

a row ofv electrically conductive printing elements mounted side-by-sidefor movement transversely to said row from a given rest position to agiven active printing position, each said element comprising a printingpoint projection, a iirst control portion, and a second control portion,each of said second con'- trol portions having a iiat surface parallelto the plane in Which the printing clement moves; first means extendingparallel to said row adjacent said first control portions andoperatively coupledfthereto for applying forces, when energized, to saidelements tending to move said elements from ythe said rest positions tothe saidactive printing positions thereof; second means extendingparallel to said row adjacent said iirst control portions andoperatively coupled thereto for applying forces, when energized, to saidelements tending to restore said elements to the said rest positions;

a series of control members arranged in a row parallel toV said row ofelements and operatively coupled respectively thereto for applyingfrictional restraining Y forces, when energized, tothe second portionsof respectiveV ones of said printingelements in the rest positionsthereof, each of said series of control members comprising a foilconstruction containing a layer of electrically conducting materialpositioned closely parallel to'the iiat surface of said element andseparated therefrom by a layer of insulating material;

means for alternately energizing said first and second i means 5 andmeans operatively connected to said energizing means and operative onlywhen said second force-applying means is energized for selectivelyenergizing said control members to apply frictional forces to selectedvones of :said second portions, thereby preventing `the correspondingprinting elements from moving tov the active printing position.

2. Printing apparatus, according` to claim 1, wherein the saidcontrol-rnember-energizing means includes:

means for applying a common electrical potential to all of said printingelements;

a series of conductive terminal members electrically connected to theconductive layers in the foil construction of corresponding ones of saidcontrol members; and

means electrically insulating said terminal members from each other.

3. Apparatus, according to claim 1, wherein each said foil constructioncomprises two symmetrically disposed foil members, one on each side ofthe second control portion of the associated printing element which,when energized by said energizing means, create a force of electrostaticattraction between said foil members and said second portion of -saidprinting element.

- References Cited by the Examiner UNITED STATES PATENTS 2,025,12312/1935 Rahbek 317-144 2,659,652 11/1953 Thompson lOl-109 2,976,8013/1961 Dirks 10d-93 2,990,767 7/1961 Deiner et al. lOl-93 WILLlAM B.PENN, Primary Examiner.

1. A PRINTING APPARATUS COMPRISING: A ROW OF ELECTRICALLY CONDUCTIVEPRINTING ELEMENTS MOUNTED SIDE-BY-SIDE FOR MOVEMENT TRANSVERSELY TO SAIDROW FROM A GIVEN REST POSITION TO A GIVEN ACTIVE PRINTING POSITION, EACHSAID ELEMENT COMPRISING A PRINTING POINT PROJECTION, A FIRST CONTROLPORTION, AND A SECOND CONTROL PORTION, EACH OF SAID SECOND CONTROLPORTIONS HAVING A FLAT SURFACE PARALLEL TO THE PLANE IN WHICH THEPRINTING ELEMENT MOVES; FIRST MEANS EXTENDING PARALLEL TO SAID ROWADJACENT SAID FIRST CONTROL PORTIONS AND OPERATIVELY COUPLED THERETO FORAPPLYING FORCES, WHEN ENERGIZED, TO SAID ELEMENTS TENDING TO MOVE SAIDELEMENTS FROM THE SAID REST POSITIONS TO THE SAID ACTIVE PRINTINGPOSITIONS THEREOF; SECOND MEANS EXTENDING PARALLEL TO SAID ROW ADJACENTSAID FIRST CONTROL PORTIONS AND OPERATIVELY COUPLED THERETO FOR APPLYINGFORCES, WHEN ENERGIZED, TO SAID ELEMENTS TENDING TO RESTORE SAIDELEMENTS TO THE SAID REST POSITIONS; A SERIES OF CONTROL MEMBERSARRANGED IN A ROW PARALLEL TO SAID ROW OF ELEMENTS AND OPERATIVELYCOUPLED RESPECTIVELY THERETO FOR APPLYING FRICTIONAL RESTRAINING FORCES,WHEN ENERGIZED, TO THE SECOND PORTIONS OF RESPECTIVE ONES OF SAIDPRINTING ELEMENTS IN THE REST POSITIONS THEREOF, EACH OF SAID SERIES OFCONTROL MEMBERS COMPRISING A FOIL CONSTRUCTION CONTAINING A LAYER OFELECTRICALLY CONDUCTING MATERIAL POSITIONED CLOSELY PARALLEL TO THE FLATSURFACE OF SAID ELEMENT AND SEPARATED THEREFROM BY A LAYER OF INSULATINGMATEIAL; MEANS FOR ALTENATELY ENERGIZING SAID FIRST AND SECOND MEANS;AND MEANS OPERATIVELY CONNECTED TO SAID ENERGIZING MEANS AND OPERATIVEONLY WHEN SAID SECOND FORCE-APPLYING MEANS IS ENERGIZED FOR SELECTIVELYENERGIZING SAID CONTROL MEMBERS TO APPLY FRICTIONAL FORCES TO SELECTEDONES OF SAID SECOND PORTIONS, THEREBY PREVENTING THE CORRESPONDINGPRINTING ELEMENTS FROM MOVING TO THE ACTIVE PRINTING POSITION.